# Laplace pressure

Written by Yuhang Jin, AP225 2011 Fall.

The Laplace pressure is the pressure difference across a curved surface or interface. This pressure jump arises from surface tension or interfacial tension, whose presence tends to compress the curved surface or interface. At equilibrium, this trend is balanced by an extra pressure at the concave side. The Laplace pressure is given as

$P_L=\gamma(\frac{1}{R_1}+\frac{1}{R_2})$,

where